Hi, are you planning to return the car to the same place? The pass you have to buy to drive on Swiss freeways/motorways/autobahns/autoroutes cost about 40 Swiss francs which you need to add on to the rental of a car in any other country but it should be on a car you rent in Switzerland already. There is also a pass required for Austrian roads - I can't recall the exact price. You will also find that petrol is least expensive in Austria as a rule. I use a company called gemut.com to rent cars because they give me the best rates possible and they have great customer service - it can all be done over the internet. You might e-mail them (the address is on the website) and ask them where they would recommend you rent. Remember that hy ou will save money by not renting at an airport and, in many places, at the train station because there are extra taxes when you rent at those places. You can return to an airport without paying the extra tax. I usually pick up the car at a city location and then return it to an airport in the same country because the drop off fees to return it to a different country are very expensive..

Hope this helps get you started.